Purification and Properties of a Thermostable Xylanase GH 11 from Penicillium occitanis Pol6

An extracellular, endo-??-1,4-xylanase was purified to homogeneity from the culture filtrate of the filamentous fungus Penicillium occitanis Pol6, grown on oat spelt xylan. The purified enzyme (PoXyn2) showed a single band on SDS?CPAGE with an apparent molecular weight of 30?kDa. The xylanase activity was optimal at pH?3.0 and 65?°C. The specific activity measured for oat spelt xylan was 2,368?U?mg^?1. The apparent K _m and V _max values were 8.33?mg?ml^?1 and 58.82???mol?min^?1?ml^?1, respectively, as measured on oat spelt xylan. Thin-layer chromatography experiments revealed that purified PoXyn2 degrades xylan in an endo-fashion releasing xylobiose as main end product. The genomic DNA and cDNA encoding this protein were cloned and sequenced. This PoXyn2 presents an open reading frame of 962?bp, not interrupted by any introns and encoding for a mature protein of 320 amino acids and 29.88?kDa.     

Preconcentration of trace environmental plutonium from iron oxide matrix using DIPEX® extractant

This paper summarizes a new method for preconcentration of rusty metal samples using DIPEX^® Actinide Resin from Eichrom Technologies prior to analysis for trace environmental actinides. This method allows for preconcentration of actinides for which the existing lanthanum coprecipitation method is ill-suited. The new and existing methods were shown to provide comparable results for plutonium analysis. Performance was compared for both lab-prepared controls and environmental samples. Using actinide resin, a mean ²³⁸Pu activity of 46 ± 13 % mBq (2σ) was measured, while ²³⁸Pu activity of 40 ± 6 % mBq (2σ) was measured using lanthanum coprecipitation. Small quantities of ^239+240Pu, likely attributable to fallout, were also detected.     

Neutron activation of traces in electrolytic zinc sulphate solutions : Simultaneous determination of mercury,uranium and ytterbium

A neutron activation determination of traces of mercury, uranium and ytterblum in electrolytic zinc sulphate solutions has been devised The isotope ¹⁹⁷Hg was measured by means of its 68-and 77-keV photopeaks Uranium was determined by measurements of the 106-keV photopeak of the ²³⁹Np daughter activity The 50- and 53-keV X-rays of ytterbium isotopes ¹⁹⁹Yb and ¹⁷⁵Yb were counted using a 1-mm thick Nal(Tl) wafer crystal The chemical separation was performed on anion-exchange resin. The matrix activities were eliminated in 185N hydrofluoric acid while the neptunium and ytterbium activities were desorbed with 5N hydrochloric acid Mercury was eluted from the column with 0.5 M thourea-0.005 N hydrochloric acid and precipitated as sulpinde     

Integral heat of dissolution of potassium chlorate in water at 298.15 K

The heat of dissolution of potassium chlorate in water at 298.15 K has been measured on an LKB 8700-1 calorimeter in the concentration range 0.063–0.659 m. The concentration dependence of the measured data was fitted by an empirical equation ΔH_m (kJ mole^?1) = 41.353₈ + 1.862₆m^{$\text{1}\text{2}$} ? 6.430₀m which was derived from our and Andauer—Lange data. The heat of crystallization calculated from this dependence was ΔH_cryst. = 34.7 ± 0.5 kJ mole^?1, which agrees with data calculated for potassium chlorate from solubility and activity data.     

Determination of 135Cs in nuclear power plant wastes by ICP-MS and k 0-NAA

A radiochemical method for the determination of ¹³⁵Cs in radioactive wastes has been adopted/developed. For the separation of cesium from other elements ammonium-molybdophosphate precipitation and cation exchange chromatography were used. The chemical yield of the method was about 60–100 %. ¹³⁵Cs was measured by two methods. In neutron activation analysis (NAA), Cs was irradiated with reactor neutrons. ¹³⁶Cs was detected by gamma spectrometry, wherefrom the activity/mass of ¹³⁵Cs was calculated according to the k ₀-standardization technique. The Cs containing fractions were measured by inductive coupled plasma mass spectrometry, as well. NAA and ICP-MS techniques were comparatively evaluated and a good agreement between the results was found. The activity concentration of ¹³⁵Cs in a couple of waste samples originating from VVER-440 type nuclear reactors was in the range of 1–5 Bq L^?1 (20–120 ng L^?1) while ¹³⁷Cs activity concentrations varied between 0.1 and 1 MBq L^?1.     

Seasonal changes of Rubisco content and activity in Fagus sylvatica and Picea abies affected by elevated CO2 concentration

We studied Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) content and activity in juvenile tree species ?? broadleaved Fagus sylvatica L. and coniferous Picea abies (L.) Karsten exposed for three growing seasons to ambient (A = 385 ??mol mol^?1) and elevated (E = 700 ??mol mol^?1) CO₂ concentrations. Rubisco content was determined by the SDS-PAGE method, Rubisco activity was assayed spectrophotometrically. The highest content of Rubisco enzyme in F. sylvatica was measured immediately after full leaf development followed by a gradual decrease throughout the growing season. By contrast, Rubisco content in P. abies increased markedly during the growing season. In both tree species, down-regulation of Rubisco content in trees cultivated under elevated CO₂ concentration was observed. Rubisco activity was stimulated in F. sylvatica by E treatment but not in P. abies. Because no significant differences were found in Rubisco activation state between A and E, we assume that stimulation of Rubisco activity in E is not a consequence of higher carbamylation but could be caused by the release of inhibitors from active sites of Rubisco under elevated CO₂.     

Liquid-phase hydrogenation of alkenes and aromatic compounds with Pd-loaded oxidized diamond catalyst

Hydrogenation reactions of alkenes (cyclohexene, ethyl acrylate, styrene and 1,5-cyclooctadiene) and aromatic compounds (o-, m- and p-xylene) were carried out in order to examine the activity of palladium-loaded surface-oxidized diamond (Pd/O-Dia) catalyst in liquid-phase hydrogenation. The catalytic performance was compared to commercial palladium-loaded activated carbon (Pd/C) catalyst. The catalyst activities were evaluated by conversions of reactants and H₂ uptake rates in the early stage of the reaction. In all the hydrogenation reactions of alkenes and aromatic compounds, the activity of Pd/O-Dia was almost the same as or slightly higher than that of Pd/C. Dispersion of Pd metal was measured by a CO-pulsed adsorption technique and TEM observations of the catalysts. Pd dispersions were on the same order of magnitude according to the CO-pulsed adsorption technique, although the Pd/C catalyst had a higher surface area (718 m²/g) than that of Pd/O-Dia (23 m²/g). The Pd particle sizes on O-Dia measured by TEM observation were slightly smaller than those on the activated carbon. Such highly dispersed Pd particles on O-Dia would contribute to higher activity for the hydrogenation reaction of alkenes and aromatic compounds.     

Study on Purification and Characterization of Polyphenol Oxidase from Acetes chinensis

Acetes chinensis (belonging to the Decapoda Sergestidae genus) is widely distributed in East Asian waters and is extremely widespread and present in the shallow coastal areas of China. Polyphenol oxidase (PPO), which was extracted from Acetes chinensis, was purified in a four-step procedure involving phosphate-buffered saline treatment, ammonium sulphate precipitation, DEAE-Cellulose chromatography, and Phenyl-Sepharose HP chromatography, and then, its biochemical characterization was measured. The specific activity of the purified enzyme was increased to 643.4 U/mg, which is a 30.35 times increase in purification, and the recovery rate was 17.9%. L-dopa was used as the substrate, the enzymatic reactions catalyzed by PPO conformed to the Michaelis equation, the maximum reaction velocity was 769.23 U/mL, and the Michaelis constant K_m was 0.846 mmol/L. The optimal pH of PPO from Acetes chinensis was 7.5, and the optimal temperature was 35 °C. The metal ions experiment showed that Mn²⁺ and K⁺ could enhance the activity of PPO; that Ba²⁺ and Ca²⁺ could inhibit the activity of PPO; and that Cu²⁺ had a double effect on PPO, increasing the PPO activity at low concentrations and inhibiting the PPO activity at high concentrations. The inhibitor experiment showed that the inhibitory effects of EDTA and kojic acid were weak and that ascorbic acid and sodium pyrophosphate had good inhibitory effects. The purification and characterization of Acetes chinensis serve as guidelines for the prediction of enzyme behavior, leading to effective prevention of enzymatic browning during processing.     

Role of melanoidins in sweet wines

Melanoidins from several Spanish sweet wines were isolated by dialysis. Browning indexes (absorbances at 420 and 345 nm) and CIELab parameters of the wines and their dialysed fractions were measured. The antioxidant activity, which was expressed as Trolox equivalent antioxidant activity (TEAC), was determined using the N,N-dimethylphenylene diamine dihydrochloride (DMPD) method.Results showed a good correlation of colour parameters L^∗, h^∗ and absorbances at 345 and 420 nm between the dialysed fractions and the original sweet wines. However, the TEAC of dialysed fractions did not show any significant correlation with TEAC of the original wines. So brown polymers of high molecular weight (>12000 Da) isolated by dialysis, which could be mainly melanoidins, play an important role on the colour of these sweet wines, but not in their antioxidant activity.     

Natural radioactivity in soil samples of Yelagiri Hills,Tamil Nadu,India and the associated radiation hazards

The natural radioactivity of soils at Yelagiri hills has been studied in this paper. The radioactivities of 25 samples have been measured with a NaI(Tl) detector. The radioactivity concentrations of ²³⁸U, ²³²Th and ⁴⁰K ranged from ≤2.17 to 53.23, 13.54 to 89.89 and from 625.09 to 2207.3 Bq kg^?1, respectively. The measured activity concentrations for these radionuclides were compared with world average activity of soil. The average activity concentration of ²³²Th in the present study is 1.19 times higher than world median value while the activity of ²³⁸U and ⁴⁰K is found to be lower. In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity Ra_eq, the absorbed dose rate D_R, the annual effective dose rate and the external hazard index (H_ex) have been calculated and compared with the internationally approved values. The study provides background radioactivity concentrations in Yelagiri hills.     

Radionuclides and trace elements in centipede species Scolopendra cingulata from Serbia

The adults of centipede Scolopendra cingulata from Serbia have been analyzed for ²¹⁴Bi, ¹³⁷Cs, ²²⁸Ac, ⁴⁰K, ²¹²Pb and ²¹⁴Pb activity. The top 5 cm of soil from the same locations (Novi Pazar, Izbice and P?inja) is also measured—to estimate upper limit of the soil–S. cingulata radionuclide transfer factors (i.e., S. cingulata/soil concentration ratios), as well as the total dose rate—external and internal exposure. Cesium-137 activity was found to be below (or equal to) minimum detectable activity in all 16 specimens. The highest measured ²¹⁴Bi activity was 0.1 Bq g^?1, while ²²⁸Ac—0.086 Bq g^?1, ⁴⁰K—0.12 Bq g^?1, ²¹²Pb—0.012 Bq g^?1 and ²¹⁴Pb—0.029 Bq g^?1. Bismut-214 transfer factors are found to range from <0.34 to 6, as ²²⁸Ac—from <0.4 to 3, whilst the total dose rate is found to be less than 18 μGy h^?1. The As, Se, Cd, Co, Cr, Cu, Mn, Ni, Pb, but also Zn and Fe concentrations—in three individuals, were also determined. All the elements showed concentrations in the P?inja S. cingulata significantly lower than in S. cingulata from Novi Pazar and Izbice.     

Excess enthalpies and (vapour + liquid) equilibrium data for the binary mixtures of dimethylsulphoxide with ketones

Excess enthalpies (H^E), at ambient pressure and T = 298.15 K, have been measured by using a solution calorimeter for the binary liquid mixtures of dimethyl sulphoxide (DMSO) with ketones, as a function of composition. The ketones chosen in the present investigation were methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CH). The H^E values are positive over the entire composition range for the three binary mixtures. Furthermore, the (vapour + liquid) equilibrium (VLE) was measured at 715 Torr for these mixtures, of different compositions, with the help of Swietoslawski-ebulliometer. The experimental temperature-mole fraction (t-x) data were used to compute Wilson parameters and then used to calculate the equilibrium vapour-phase compositions as well as the theoretical points for these binary mixtures. These Wilson parameters are used to calculate activity coefficients (γ) and these in turn to calculate excess Gibbs free energy (G^E). The intermolecular interactions and structural effects were analyzed on the basis of the measured and derived properties.     

Non-destructive proton activation analysis for nitrogen in refractory metals

The non-destructive determination of nitrogen in some refractory metals was studied by activation analysis with the ¹⁴N(p, n)¹⁴O reaction. The samples were irradiated with 12-MeV protons from a cyclotron. The proton beam intensity was normalized by means of a copper flux monitor. After chemical etching, the ¹⁴O activity (E_γ = 2313 keV, T_{$\text{1}\text{2}$} = 70.5 s) of the sample was measured by means of a Ge(Li) or NaI(Tl) detector. Standardization was carried out by the “average cross-section” method with nylon 6 as a nitrogen standard. The method gives a sensitivity of 0.4–30 μg g^?1 for analysis of Ta, W, Nb, and Ti, and 2000–4000 μg g^?1 for Zr, Ni and Mo.     

Solubility enhancement of phenanthrene using novel chelating surfactant

A novel chelating surfactant denoted as sodium N-lauroyl ethylenediamine triacetate (N-LED3A) with both surface activity and chelation functions was studied for phenanthrene (PHE) solubilisation ability. The critical micelle concentration (CMC) of N-LED3A was measured, and the effects of the initial N-LED3A concentration, temperature, pH value and coexisting ions (Na⁺, Ca²⁺ and Cu²⁺) on PHE solubilisation by N-LED3A were investigated. The results demonstrated that PHE solubility was efficiently enhanced by N-LED3A, especially with N-LED3A concentrations above the CMC, which was 707 mg L^?1 when measured at 25°C. The temperature influenced the apparent PHE solubility slightly and the apparent solubility of PHE was significantly affected by the pH. Na and Ca were shown to increase the PHE solubility, while Ca exhibited a better promoting ability than Na⁺. A suitable quantity of Cu could significantly enhance the solubilisation capacities of N-LED3A at pH 5. The mechanism of the interaction between Cu⁺ and N-LED3A was further confirmed by Fourier transform infrared spectroscopy (FTIR). These results reveal that Cu²⁺ can be chelated with N-LED3A to form a chelate complex. The results implied that N-LED3A had the potential to remediate soils contaminated by both organics and heavy metals.     

Inhibiting effect of 5-amino-5-methyluracil and its derivatives on the free-radical oxidation of 1,4-dioxane

The antiradical activity of 5-amino-6-methyluracil in the initiated radical-chain oxidation of 1,4-dioxane as a model system was studied quantitatively. The rate constant k ₇ of its reaction with the peroxyl radical of 1,4-dioxane was measured to be (5.6 ± 1.8) × 10⁵ L mol^?1 s^?1 at 333 K. The effect of the methyl substituents in the 1- and 3-positions of the uracil ring and in the amino group on the rate constant of inhibition was studied. The strengths of all N-H bonds in the 5-amino-6-methyluracil and its derivatives were calculated in the G3MP2B3 approximation and were compared with the measured rate constants of inhibition. By the example of the reaction of 5-amino-6-uracil with i-PrO ₂ ^?? , different attack pathways of the peroxyl radical at the N-H bonds of uracil were analyzed in the UB3LYP/6-311+G(d,p) approximation. The lowest activation barrier (5.8 kJ/mol) was observed for peroxyl radical attack on the (C⁵)N-H bonds. The site responsible for the inhibition activity of the compound is the amino group.     

Determination of human serum semicarbazide-sensitive amine oxidase activity via flow injection analysis with fluorescence detection after online derivatization of the enzymatically produced benzaldehyde with 1,2-diaminoanthraquinone

A fast, simple, and sensitive flow injection analysis method was developed for the measurement of semicarbazide-sensitive amine oxidase (SSAO) activity in human serum. Benzaldehyde, generated by the action of SSAO after incubation of serum with benzylamine, was derivatized with a novel aromatic aldehyde-specific reagent (1,2-diaminoanthraquinone) and the fluorescent product was measured by fluorescence detection at excitation and emission wavelengths of 390 and 570 nm, respectively. Serum SSAO activity was defined as benzaldehyde (nmol) formed per milliliter serum per hour. The method was linear over SSAO activity of 0.2–150.0 nmol mL⁻¹ h⁻¹ with a detection limit of 0.06 nmol mL⁻¹ h⁻¹. The %RSD of intra-day and inter-day precision did not exceed 9.4% and the accuracy ranged from −6.5 to −0.6%. The method was applied for the determination of the serum SSAO activity in healthy controls (C, n = 24) and diabetes mellitus patients (DM, n = 18). It was demonstrated that the activity (mean ± SE) of SSAO in diabetics sera was significantly higher than that in healthy subjects’ ones (DM; 73.3 ± 1.8 nmol mL⁻¹ h⁻¹vs C; 58.9 ± 2.2 nmol mL⁻¹ h⁻¹, P < 0.01).     

VT-NMR and cytotoxic evaluation of some new ortho-(alkylchalcogen)acetanilides

Several novel atropisomeric N-alkyl-N-[(2-alkylchalcogen)phenyl)]acetamides have been synthesized and fully characterized by ¹H and ¹³C NMR, FTIR, and HRMS (FAB). The barriers of the restricted rotation about the N-aryl bond between the two atropisomeric forms were measured by accurate lineshape simulation of variable temperature NMR (VT-NMR) spectra obtained in DMSO-d₆ solution and ranged from 17.0 to 20.5 kcal/mol. The relationship between the structure of the different acetanilide moieties and both coalescence temperature and energy of rotation are herein discussed. Taking in mind the acetamide structural resemblances with nimesulide related compounds known by their anticancer activity, the in vitro cytotoxicity of 20 representative acetanilides, against human breast (MCF-7) and prostate (LNCaP) cancer cell lines as well as normal human dermal fibroblasts (NHDF) was also preliminary evaluated. Interestingly a selective antiproliferative activity was observed for cancerous cells with prominence to LNCaP within the most potent O- and/or N-benzylic and -hexyl acetanilides.     

Antiradical activity of 5-amino-1,3,6-trimethyluracil in the radical chain oxidation of ethylbenzene as the model system

The antiradical activity of 5-amino-1,3,6-trimethyluracil was quantitatively measured in the initiated radical chain oxidation of ethylbenzene as the model system. The rate constant of the reaction of 5-amino-1,3,6-trimethyluracil with the ethylbenzene peroxyl radical at 333 K was found: k ₇ = (2.1 ± 0.3) × 10⁵ L mol^?1 s^?1. The kinetics of 5-amino-1,3,6-trimethyluracil consumption in the course of the radical chain oxidation of ethylbenzene was studied. The stoichiometric inhibition factor was determined to be f = 2.     

Thermodynamic functions of the mixing of methacrylic acid in organic solvents

The saturated vapor pressure over solutions of methacrylic acid is measured tensimetrically in acetonitrile, benzene, hexane, 1,2-dichloroethane, and acetic acid is measured tensimetrically at 290–350 K. The composition of equilibrium phases, the activity coefficients of the components, and the thermodynamic functions of the mixing (H ^E , G ^E , S ^E ) of the investigated solutions are calculated from the temperature dependence data.     

Evolution and solar modulation of 7Be during the solar cycle 23

The modulation of ⁷Be-aerosols concentration due to solar activity during the cycle 23 is studied in the present research. For that purpose, was analyzed the differences in the long-term variation of geomagnetic and solar activity to assess the physical effects over the evolution of ⁷Be during the period 1996–2010. Furthermore, exploratory data analysis was applied to understand better the behavior of ⁷Be-aerosols in the surface atmosphere. This study shows that there is an inverse relationship among ⁷Be measured in the near ground air and solar activity. The modulation of ⁷Be-aerosols during the cycle 23 was divided in two steps. In the first stage, ascending phase, 1996–2002, the solar activity played an important role in the production rate of ⁷Be, r = ?0.75. However, during the descending phase, 2002–2009, the role of the solar activity was secondary, r = ?0.30, allowing that ⁷Be-aerosols reached the maximum concentration, 9.33 mBq m^?3 in August-09 when the solar activity was zero. Moreover, the remaining solar activity after the end of the ascending phase and the last important solar storm (December-06) caused the slowdown of ⁷Be production rate from 2001 to 2004 and the rupture of the seasonal behavior of ⁷Be in 2007, respectively. Finally, this research highlight the necessity to take into account the solar cycle phase, ascending or descending, to model studies of atmospheric process with ⁷Be as tracer since the contribution of the variables studied are so different in these stages.